1. Field of the Invention
The present invention relates to a wiring structure of a touch panel used in a touch-panel input device that gives a feeling of input manipulation to a manipulator who presses a movable plate, since the movable plate being pressed or a supporting substrate supporting the movable plate is allowed to vibrate. In particular, the present invention relates to a wiring structure of a touch panel that allows the movable plate or the supporting substrate to vibrate using a piezoelectric substrate.
2. Description of the Related Art
A touch panel is used in a touch-panel input device. The touch-panel input device is a device in which a movable plate and a supporting substrate are deposited with a slight insulation gap between conductive layers formed on their respective opposing surfaces. When the movable plate is pressed, the touch-panel input device electrically detects that the opposing conductive layers come in contact with each other at the pressed position and outputs the pressed position data to each processing device.
The touch-panel input device of this kind has a lamination structure in which the movable plate and the supporting substrate are deposited with a slight insulation gap in between. Hence, the pressing stroke of the movable plate is in an extremely small range from tens to hundreds microns, which makes it difficult to give a feeling of input manipulation to the manipulator. To eliminate this inconvenience, a force feedback type touch panel is adopted, in which the movable plate or the supporting substrate is allowed to vibrate when the movable plate is pressed, so that the manipulator has a feeling of input manipulation at his or her fingertip when pressing the movable plate.
The applicant of the present application filed earlier another patent application (Japanese Patent Application No. 2001-312399) describing the invention as follows, which is related to a touch panel that allows the movable plate or the supporting substrate to vibrate in such a manner that the manipulator can detect the vibration, using a simple driving circuit.
That is, the patent application of the previous invention discloses a touch-panel input device arranged in such a manner that a pair of driving electrodes is fixed to the respective opposing surfaces of the piezoelectric substrate, and the piezoelectric substrate is fixed to the movable plate or the supporting substrate directly or through the driving electrodes. Thus, upon detection of pressing on the input manipulation surface, the movable plate or the supporting substrate is allowed to vibrate by the piezoelectric substrate that expands and contracts in association with application of a driving voltage to the pair of driving electrodes.
The present invention relates to an improvement of the wiring structure of the touch panel of the previous invention described in the above patent application.
A touch panel comprises the movable plate on the back surface of which is formed a conductive layer and a supporting substrate on the top surface of which is formed a conductive layer with a slight wiring gap in between, and the piezoelectric substrate is fixed to the movable plate or the supporting substrate. For a touch panel having such a structure, it is necessary to withdraw a wiring to the movable plate and the supporting substrate and a driving wiring for the piezoelectric substrate.
When these wirings are withdrawn separately and connected to connectors, for example, when two piezoelectric substrates are provided on either end of the supporting substrate, three connectors are necessary in total; moreover, the wiring becomes complicated.
Accordingly, the weight and the size of the touch panel cannot be reduced sufficiently.
Also, neither the structure of merely sandwiching the piezoelectric substrate between the movable plate and the supporting substrate nor the method of fixing the piezoelectric substrate to the back surface of the supporting substrate can reduce the thickness of the touch panel sufficiently.